Neural stimulation has been proposed as a therapy for a number of conditions. Examples of neural stimulation therapies include neural stimulation therapies for respiratory problems such a sleep disordered breathing, blood pressure control such as to treat hypertension, cardiac rhythm management, myocardial infarction and ischemia, heart failure, epilepsy, depression, pain, migraines, eating disorders and obesity. Neural stimulation therapies can involve intermittent neural stimulation.
At the 2006 European Society of Cardiology meeting, De Ferrari et al. showed preliminary results from a study of chronic vagal nerve stimulation study in heart failure patients, where Class III heart failure patients were provided six months of therapy, uncontrolled, using an implantable vagal stimulator designed to reduce heart rate. The stimulator delivered selective efferent stimulation to the vagus nerve, targeted to slow the heart rate, and used sensed heart rate as a negative feedback therapy control that delivers vagus nerve stimulation when the heart rate is elevated and shuts off vagus nerve stimulation when the heart rate falls below a threshold. The stimulator continuously delivered vagus nerve stimulation when the heart rate is elevated, and synchronized the vagus nerve stimulation with the heart rate. The data indicated improvement over the first three months with regression over the next three months. De Ferrari et al. hypothesized that the regression was due to the severity and unstoppable progression of the underlying disease.